Question

Find the tens digit of the cube root of each of the numbers in Q. No. 15.

Answer 1

(i) Let us consider the number 226981.
The unit digit is 1; therefore, the unit digit of the cube root of 226981 is 1.
After striking out the units, tens and hundreds digits of the given number, we are left with 226.
Now, 6 is the largest number, whose cube is less than or equal to 226 ($6^3<226<7^3$).
Therefore, the tens digit of the cube root of 226981 is 6.

(ii) Let us consider the number 13824.
The unit digit is 4; therefore, the unit digit of the cube root of 13824 is 4.
After striking out the units, tens and hundreds digits of the given number, we are left with 13.
Now, 2 is the largest number, whose cube is less than or equal to 13 ($2^3<13<3^3$).
Therefore, the tens digit of the cube root of 13824 is 2.

(iii) Let us consider the number 571787.
The unit digit is 7; therefore, the unit digit of the cube root of 571787 is 3.
After striking out the units, tens and hundreds digits of the given number, we are left with 571.
Now, 8 is the largest number, whose cube is less than or equal to 571 ($8^3<571<9^3$).
Therefore, the tens digit of the cube root of 571787 is 8.

(iv) Let us consider the number 175616.
The unit digit is 6; therefore, the unit digit of the cube root of 175616 is 6.
After striking out the units, tens and hundreds digits of the given number, we are left with 175.
Now, 5 is the largest number, whose cube is less than or equal to 175 ($5^3<175<6^3$).
Therefore, the tens digit of the cube root of 175616 is 5.